Grammar can be a tough nut to crack, and there are times when a few mistakes here and there can determine whether or not you get a job or an A on your paper. Grammarly is a web app that scrutinizes your sentence structure to find errors and help you correct them.

It'll check any text for free and let you know what the errors are, but you'll need an account to get the specifics. Those accounts don't come cheap, starting at $30 per month (with much steeper discounts if you pay by the year). Nevertheless, you can try it out for seven days. If you feel it's worth the money you can continue, but if you just have a resume and cover letter to check you can do that much for free. In my tests, Grammarly does a pretty good job of pointing out potential issues. It errs on the aggressive side—so much so that it thought part of this post was plagiarized—but you can always ignore its suggestions if you don't agree.